Device and Method of Estimating Symbol Using Second Order Differential Phase Vector

1. A symbol estimation apparatus comprising: a phase component derivation unit to derive phase components of input data; a second order differentiator to apply a second order differentiation to the phase components to obtain a second order differential phase vector; and a symbol estimator to estimate symbols corresponding to the input data using the second order differential phase vector.

2. The symbol estimation apparatus of claim 1 , wherein the second order differentiator comprises: a first differentiator to generate a first order differential phase vector with respect to the phase components using a smoothing window that equalizes the phase components; and a second differentiator to differentiate the first order differential phase vector to obtain the second order differential phase vector.

3. The symbol estimation apparatus of claim 1 , wherein the second differentiator uses an n th phase component and at least two phase components adjacent to the n th phase component among the phase components to obtain an n th element included in the second order differential phase vector.

4. The symbol estimation apparatus of claim 1 , wherein the symbol estimator comprises: a modulation scheme determining unit to determine a modulation scheme of the input data using a variance of the second order differential phase vector.

5. The symbol estimation apparatus of claim 4 , wherein the modulation scheme determining unit determines the modulation scheme of the input data by comparing the variance of the second order differential phase vector with a predetermined value.

6. The symbol estimation apparatus of claim 1 , further comprising: an amplitude vector detector to detect an amplitude vector comprising amplitude components of the input data, wherein the symbol estimator estimates the symbols using the amplitude vector and the second order differential phase vector.

7. A method of estimating a symbol, comprising: deriving phase components of input data; applying a second order differentiation to the phase components to obtain a second order differential phase vector; and estimating symbols corresponding to the input data using the second order differential phase vector.

8. The method of claim 7 , wherein the applying comprises: deriving a first order differential phase vector with respect to the phase components using a smoothing window that equalizes the phase components; and differentiating the first order differential phase vector to obtain the second order differential phase vector.

9. The method of claim 7 , wherein the applying comprises: using an n th phase component and at least two phase components adjacent to the n th phase component among the phase elements to obtain an n th element included in the second order differential phase vector.

10. The method of claim 7 , wherein the estimating comprises: determining a modulation scheme of the input data using a variance of the second order differential phase vector.

11. The method of claim 10 , wherein the determining comprises determining the modulation scheme of the input data by comparing the variance of the second order differential phase vector with a predetermined value.

12. The method of claim 7 , further comprising: detecting an amplitude vector comprising amplitude components of the input data, wherein, the estimating comprises estimating the symbols using the amplitude vector and the second order differential phase vector.

13. The method of claim 12 , wherein the estimating comprises estimating the symbols using a combination of the amplitude vector and the second order differential phase vector.

14. The method of claim 12 , wherein the estimating comprises adjusting the amplitude vector based on the second order differential phase vector, and estimating the symbols using the adjusted amplitude vector and the second order differential phase vector.

15. A method of compensating for a frequency offset, comprising: deriving phase components of input data; deriving a first order differential phase vector with respect to the phase components using a smoothing window that equalizes the phase components; and differentiating the first order differential phase vector to automatically compensate for a frequency offset of the input data.

16. The method of claim 15 , further comprising: determining a modulation scheme of the input data using a variance of the second order differential phase vector that is generated by differentiating the first order differential phase vector.